Leap second will be added before the midnight of Dec. 31. The information was announced by the authorities from the International Earth Rotation and Reference Systems Service and make clocks in sync with the change of the Earth's rotation.

The leap second is added to keep clocks in sync with the change of the Earth's rotation angle. The last leap second was added on June 30, 2012 and June 30, 2015, respectively. There is a total of 26 leap seconds that have been added to atomic clocks since the tradition was started in 1972 by IERS, NIST reported.

A leap second's unit of time is defined based on Earth's rotation in relation to the distant celestial bodies, but this has changed with the atomic clock debut. At present, this has led to an accurate timekeeping; losing about a second of accuracy every 300 million years only, Data Center reported.

The Earth's rotation does not stay steady. It has slowed down by about .0015 to .002 seconds per day each century. For more accurate timekeeping, leap second addition has been developed. The main purpose of adding a second is to keep the two timescales within 0.9 seconds apart from each other.

The leap second tradition made in 2012 created technical problems amongst big technical companies such as LinkedIn, Reddit, The Mozilla Foundation, and others.

Google reportedly has encountered some problems in 2005 leap second addition; however, the "leap smear" has fixed the issue. With this, the company added a few milliseconds throughout the day to its server clocks so that their servers are sync when UTC will do the time change.

A leap second is always inserted on June 30 or Dec. 31 of a certain year. Natural events such as the moon's gravitational force, earthquake, volcanic eruptions, tidal waves or other geological phenomena have a huge effect on the Earth's rotation. With these, studies show that the earth's rotation is slowing over time.